1. Field of the Invention
The present invention relates to a capsule medical device guidance system and a method for guiding a capsule medical device in which a capsule medical device to be inserted inside a subject is guided.
2. Description of the Related Art
Conventionally, a capsule medical device provided with an imaging function and a radio communication function within a casing of a capsule shape formed in a size allowing insertion into an inside of a digestive canal of a subject such as a patient has appeared in the field of an endoscope. The capsule medical device, after being swallowed from a mouth of the subject, travels inside the digestive canal according to its peristalsis and the like. The capsule medical device sequentially obtains images inside organs of the subject (hereinafter sometimes referred to as “in-vivo images”) and sequentially transmits the obtained in-vivo images wirelessly to a receiver placed outside the subject until it is naturally excreted after inserted inside the digestive canal of the subject.
The in-vivo images captured by the capsule medical device are imported into an image displaying device via the receiver. The image displaying device displays the imported in-vivo images statically or dynamically. A user such as a doctor or a nurse observes the in-vivo images of the subject displayed on the image displaying device to examine the inside of organs of the subject through the observation.
Besides, a capsule medical device guidance system in which the capsule medical device inside the subject is guided by a magnetic force (hereinafter referred to as a “magnetic guidance”) has been proposed in recent years. In the capsule medical device guidance system, the capsule medical device is generally further provided with a permanent magnet inside the capsule-shaped casing and the image displaying device displays the in-vivo images sequentially captured by the capsule medical device inside the subject in real time. In the capsule medical device guidance system, a magnetic field is applied to the capsule medical device inside the subject and the capsule medical device inside the subject is magnetically guided to a desired position by the magnetic force generated by the applied magnetic field. The user uses an operation unit of the capsule medical device guidance system to operate the magnetic guidance of the capsule medical device while referring to the in-vivo images displayed on the image displaying device.
As the capsule medical device, a capsule endoscope which, for observing the inside of organs such as a stomach or a large intestine having a comparatively large space, has a specific gravity enabling floating on a liquid injected inside such organs and sequentially captures in-vivo images in a floating state on the liquid is available. To examine the inside of the organs such as a stomach having a comparatively large space intensively, there is a case in which a liquid which makes the inside of the organ (a fold of an inner wall of the organ, specifically) stretch and the capsule endoscope having a lower specific gravity than the liquid are ingested (see International Publication No. 2007/077922, for example). In this case, the capsule endoscope sequentially captures images inside the organ which has stretched due to the liquid while floating on a surface of the liquid in a manner of taking a predetermined attitude (a vertical attitude in which a central axis in a longitudinal direction of the capsule endoscope becomes perpendicular to the surface of the liquid, for example) in the inside of the organ such as a stomach. The capsule endoscope is capable of capturing images inside the organ over a wide range by travelling in a desired direction in the state of floating on the surface of the liquid inside the organ.